Just to clarify are you referring to your phone storage being full?
Sorry to you are going through this sounds like the backup wasn't done. Follow these directions on the bottom to fix your issue.
From Settings, tap Accounts and backup, and then tap Samsung Cloud. Tap More Options and then tap Settings. Next, tap Sync and auto-backup settings, and then tap the Auto back up the tab. Here, you can adjust which options get backed up automatically; tap the switch next to your desired apps.
Could you possible provide screenshots so we can confirm what type of storage issue youre experiencing. I need to clairfy some details to make sure you get the best solutions. Is your cloud storage full or your internal memory of the device full?